1. Field of the Invention
Embodiments of the present invention relate to a semiconductor memory device, and more particularly, to a semiconductor memory device and a semiconductor memory system for compensating crosstalk.
2. Description of the Related Art
When a signal is transmitted through a channel, crosstalk occurs due to a signal transmitted through a neighboring channel. Crosstalk refers to a phenomenon in which electrical coupling between signals transmitted through different channels, e.g., capacitive coupling, electronic coupling, or the like, affects other channels. The crosstalk contributes to limiting a maximum operating frequency of a channel and a system. A voltage difference and a timing difference occur between transmitted signals due to the crosstalk. The timing difference varies depending on whether a transmitted signal is in phase or out of phase with a signal transmitted through a neighboring channel.
FIG. 1 is a block diagram of a conventional semiconductor memory device transmitting signals through channels.
FIG. 2A illustrates waveforms of a transmitted signal and neighboring signals that are in phase with one another, and FIG. 2B illustrates waveforms of a transmitted signal and neighboring signals that are out of phase with one another.
Referring to FIGS. 1 and 2A, if transmitted signals T1, T2, and T3 are in phase with one another, signals R1, R2, and R3 are received as shown in FIG. 2A. In other words, when the transmitted signals T1, T2, and T3 are in phase with one another, inductance among neighboring channels increases. Thus, the signal R2 is transmitted later than the signals R1 and R3 that are adjacent to the signal R1.
Referring to FIG. 1 and 2B, if the transmitted signals T1, T2, and T3 are out of phase with one another, i.e., the transmitted signals T1 and T3 are out of phase with the transmitted signal T2, signals R1, R2, and R3 are received as shown in FIG. 2B. In other words, when the transmitted signals T1, T2, and T3 are out of phase with one another, inductance among neighboring channels decreases. Thus, the signal R2 is transmitted faster than the signals R1 and R3 that are adjacent to the signal R2.